The beverage industry continually strives for machinery and methods which facilitate rapid, economical and efficient filling of containers, such as bottles or cans, with carbonated liquids. Improved machinery for filling containers with carbonated liquids and improved filling valves for rapidly and efficiently filling these containers are therefore desirable. These machines and valves must ensure that the carbonated liquid which fills the containers under pressure does not escape from the machine during filling, and that the carbonation does not escape from the liquid as the container is filled.
Methods and apparatus for filling containers with carbonated liquids have evolved into counterpressure filling machines in which the containers are first filled with a gas under pressure, for example, CO.sub.2, at about 40 psi. The carbonated liquid is thereafter admitted to the containers under pressure so that the carbonated liquid does not escape. The containers are then quickly closed, thereby ensuring that the carbonation does not escape the liquid. An example of a filling valve in a carbonated liquid bottling machine is shown in U.S. Pat. No. 4,089,353, Antonelli, which is commonly assigned. The teachings of the Antonelli patent are specifically incorporated herein by reference.
In the Antonelli patent, a filling valve is shown which connects a container with a tank containing a supply of the liquid which will fill the container, and a supply of the pressurized gas for counterpressurizing the container. The filling valve is controlled by a cam outside of the tank which actuates a first valve member such that the counterpressure gas is first admitted to the container. The container is filled with the counterpressure gas until the pressures of the gas and the liquid are equal. A second valve member is then opened by the cam which allows the liquid to flow into the container under the influence of gravity. When the container is filled, the cam actuator closes the valve members and the bottle is lowered away from the valve in a sequenced operation.
In exemplary machines for filling cans employing the principles of the Antonelli patent, a plurality of filling valves are mounted to the machine on a bottom circular surface. The cans which are to be filled are carried along a conveyer to lifters which move along a path under the filling valves. Examples of such filling valves are found in U.S. Pat. No. 4,750,533, Yun, which is commonly assigned. The Yun patent teaches a filling valve for filling cans with a pressurized fluid wherein the can is lifted to the filling valve. Each can is carried to a lifter which moves the can vertically upward to the filling valve. The lifter and the can are then moved in a circular path with the filling valve as the can is filled with the carbonated liquid. After the can is filled, the lifter lowers the can away from the valve. Machines which utilize lifters are relatively complex and expensive, and require complex structures to support the lifters as they cooperate with the filling valves.
To reduce the cost and complexity of such can filling machines, machines have been developed in which the cans are not elevated toward the filling valves, but rather, remain stationary in a vertical direction while the filing valve is lowered to meet the can. Although these machines are mechanically less complicated and substantially less expensive to produce, they have a severe disadvantage due to a reduced operating speed.
The filling valves which are used in these stationary can machines generally include two concentric valve members. As outer valve member for admitting liquid into the container is provided, and an inner valve member for admitting counterpressure gas into the container is further provided. The outlet dispensing end or "vent tube" for the inner valve member must be inserted a certain distance into the container for proper operation of the filling valve. To achieve this action, the filling valve must have a relatively long stroke to meet the containers, thereby ensuring that the outlet of the vent tube is inserted the proper depth in the container and that the vent tube is lifted clear from the container after the container is filled with the carbonated liquid. The requirement of moving the filling valves along this relatively long stroke significantly slows down the overall operation of stationary container filling machines.
Examples of filling machines having movable filling valves may be found in U.S. Pat. No. 4,679,603, Rademacher et al. The Rademacher et al. patent discloses a filling valve which can be lowered into the filling position by a cam disk and a pressure spring, or which can be lowered into position by overpressure within the filling machine vessel. A centering member within the filling valve can similarly be moved into position with the container. An upwardly extending piston member forming part of the piston-cylinder unit contains a return gas tube which can move independently of the piston-cylinder unit. The piston-cylinder unit in cooperation with a double lever arm arrangement places the filling valve in the open condition to achieve complete pressure equalization. See column 1, line 58, through column 2, line 15.
The filling valves disclosed in the Rademacher et al. patent do not fulfill a long-felt need in the art for filling valves that perform fast and efficient filling of containers with carbonated liquids. The use of the double arm lever arrangement disclosed in the Rademacher et al. patent for allowing independent movement of the return gas tube with respect to the valve is cumbersome and requires complex mechanisms to actuate valve movement. These complex mechanisms are costly, and greatly add to the time it takes for the filling valve to be lowered into position over the container which will be filled with the carbonated liquids.
The filling valves described above do not satisfy a long-felt need in the art for filling valves which can efficiently and expeditiously fill a large number of filling cans in a counterpressure filling machine. Filling valves which would satisfy this need should have a shortened vent tube stroke and be movable to interface with stationary containers which will be filled with carbonated liquids.